Project Summary/Abstract Title: Metabolic drivers and sensors of cell proliferation in pulmonary hypertension Key Words: Pulmonary hypertension, glucose metabolism, O-GlcNAc, cell proliferation K99 pathway to R00 independence: The applicant took a unique opportunity to join the Cleveland Clinic Pathobiology Department for his postdoctoral training to gain experience in human translational research. The K99 application will combine his pre-doc expertise in basic research and his post-doc translational/clinical research to create an independent, translational career. By the end of the 2 year K99 portion of the award, he will have established an animal model for pulmonary hypertension, acquired the necessary skills to interrogate this model for the 3-year R00 transition, and link this it to his continued study of human clinical research. Research Plan: Idiopathic pulmonary arterial hypertension (IPAH) is a progressive disease that leads to deterioration in cardiopulmonary function and premature death. Presently, IPAH is considered a vasculopathy, and metabolic dysregulation, including dysregulated glucose metabolism, has emerged as a major area of research in the pathobiology of the disease. Several processes may be governed by the metabolic dysfunction present in IPAH, including enhanced pulmonary vascular cell proliferation, vascular remodeling, and vasoconstriction. Thus, there is a clear need for more effective therapies that target the underlying disease processes in IPAH. We recently published that increased O-linked N-acetyl-glucosamine (O-GlcNAc) transferase (OGT) activity was shown to enhance pulmonary arterial smooth muscle cell proliferation and worsen IPAH disease outcomes. OGT is a molecular stress `sensor' and is responsible for the O-GlcNAc modification of proteins that are involved in cell signaling, cell cycle, proliferation, and nutrient metabolism. Proper homeostasis of the OGT/O-GlcNAc axis is required for cell viability and regulation. When elevated and sustained, the OGT/O-GlcNAc axis is a `driver' of disease pathology through the marked regulation of fundamental processes, including cell proliferation and nutrient metabolism. On the other hand, instant and temporary homeostatic changes within the OGT/O-GlcNAc axis can protect cells from the onset of oxidative stress, hypoxia, trauma hemorrhage, and ischemia/reperfusion injury. The central hypothesis of this proposal is that HBP flux and the OGT/O-GlcNAc axis is fundamental to protect the lung vasculature in the early progression of IPAH, while excessive and sustained levels lead to the `end-stage' of the disease. Using a combination of models ranging from human cell culture to animal models, we will test our hypothesis by investigating the following specific aims: AIM 1 (K99; human clinical training and transition): Determine the mechanism(s) whereby the OGT/O-GlcNAc axis regulates glucose utilization and metabolism in IPAH. AIM 2 (K99, R00): Investigate the specific molecular regulator(s) of the OGT/O-GlcNAc axis in the pathogenesis of IPAH and a hypoxia/sugen mouse model. AIM 3 (R00, independence): Determine the role of the increased OGT/O-GlcNAc axis in the early progression of PAH using a hypoxia/sugen mouse model. The proposed K99/R00 application is innovative because it: (i) utilizes didactic training leveraged through the interaction between the Programs of Excellence in Glycoscience (PEG) sites (Cleveland Clinic and Johns Hopkins University) as well as other significant sites (New York University and University of Illinois-Chicago); (ii) evokes translational research from both human IPAH samples and hypoxia/sugen mouse models to determine the molecular regulators that contribute to the imbalance of the OGT/O-GlcNAc axis and its impact on aberrant glucose metabolism and cell proliferation in IPAH; and (iii) launches long-term, core collaborations between the PI, established scientists in the field of glycobiology, and clinicians/scientists in pulmonary vascular disease. The project will identify the sensors and drivers of the glucose metabolism and cell proliferation, improve our understating of IPAH pathogenesis and progression, and offer new insights into the pathobiology of IPAH to ultimately improve patient functional capacity, quality of life, and long-term survival.